1. Field of the Invention
This invention relates to an overhead support system and is, more particularly, concerned with such a system for use in theatres to provide an overhead suspension track for curtains or other suspended apparatus or people.
2. Brief Description of the Prior Art
In known overhead track systems, open-ended elongated track or rail members of box-like section have been employed using an elongated slot extending along a lower side and formed of folded steel sheet metal to provide a rigid elongated support member within which pulley support means may run with a suspension support downwardly depending therefrom through the slot. Curtains, stage props or other theatrical apparatus is attached to the suspension support whereby movement of the pulley support means carries the curtains, props or apparatus along the path determined by the track or rail member.
Difficulties and problems have been encountered in joining adjacent ends together of track or rail member sections in order to provide a pulley support means path longer than the length of a single track or rail member. Usually, a coupler is used to connect the opposing ends of track members in proper alignment to permit smooth travel of the pulley support means. The conventional coupler comprises a pair of splice plates positioned on either side of the abutting opposing ends of track members so as to reinforce the joint. Each splice plate comprises an upper flange formed with a lower portion of half box-form such that when the upper flange portions of a pair of are abutted the half-box portions may embrace the box-like section of the track or rail member. These latter portions include lower facing edges of the half-box portions being spaced apart sufficiently to avoid obstructing the slot of the track member. The splice members are assembled by bolts passing through the abutting flange portions, and the sides of the half-box portions are provided with an array of threaded apertures into which bolts are screwed for engaging the external surfaces of the track member to secure it therein. The splice plates are formed from folded, steel sheet metal pieces and the half-box portions provide a large clearance fit around the track member box-section. The bolts in the threaded apertures serve to take up the clearance and to center the track member such that two track members may be substantially precisely aligned within the splice. This is time consuming and requires skill and care to avoid obstruction in use due to slight misalignment of the track members. The large number of bolts required presents difficulties in assembly, storage and transport of a support system comprising a multiplicity of track members and splices and also present external projections in assembled use which may present hazards to lines, ropes, chains or the like used with the system for supporting and traversing purposes. Also, by constructing the splice plate from sheet steel, the joint is not sufficiently reinforced to prevent wobble during movement of the pulley support means. Although the use of steel would seem to be strong, the opposite is true since the form of metal is sheet. The use of steel is heavy and does not constitute a high strength-to-weight ratio.
Therefore, a long standing need exists to provide a coupling means for abutting opposing ends of aligned track or rail members which is lightweight, strong and convenient to transport as well as to install.